Why is proper evacuation of the MVAC system crucial before recharging?

Proper evacuation of the MVAC (Motor Vehicle Air Conditioning) system is essential primarily to eliminate moisture and contaminants that could negatively impact the system's performance and longevity. When moisture is present in an air conditioning system, it can lead to the formation of ice and acids, which may cause corrosion and blockages. Additionally, contaminants such as debris or old refrigerants can reduce the efficiency of the cooling process, potentially damaging the compressor or other components. Thus, ensuring that the system is evacuated properly helps maintain optimal operation and prolongs the life of the vehicle's air conditioning system.